What is the only Great Lake without an international border? Of these five, only Lake Michigan is fully within the United States. The remaining four, Lakes Huron, Ontario, Erie, Superior are bisected by the international border separating the United States and Canada.
Lake Superior is the world's largest freshwater lake by area (31,700 mi2 /82,100 km2). It is also the coldest and deepest of the Great Lakes, with a maximum depth of 406 meters (1,332 feet). By most measures, it is the healthiest of all the Great Lakes.
Geology of Lake InferiorLake Inferior is an underground lake that is located beneath Lake Superior. It is believed to be formed by a process known as karstification, which is the dissolution of limestone and dolomite rock. This process creates sinkholes, caves, and underground rivers and lakes.